Spray nozzle assembly operable at low pressure

ABSTRACT

Paint sprayer with nozzle mounted in a chamber of an air cap adapted to be secured to a conventional compressed-air gun adjacent separate paint and air outlets therefrom.

Inventors Nathaniek Hughes [56] References Cited Beverly 11111115; UNITED STATES PATENTS MmG'Mdmmyamlmybmhofi 2,570,190 10/1951 Ballard 239/424.5x

l N 2,737,419 3/1956 Marcuse 239/428X P S 1969 2,991,015 7/1961 Standlick 239/428X F116 d 278 1971 3,330,484 7/1967 Johnson m1. 239/42sx 3,477,647 11/1969 Grundmanetall. 239/600X Ass1gnee Emery Se1ences,llncorporatedl El Segundo m Primary Examiner-M. Henson Wood, Jr.

SPRAY NUZZJLE ASSEWLY UPIEMELHB A11" LOW Assistant ExaminerThomas C. Culp, Jr.

Attorney-Wm. W. Rymer PRESSURE 7 Claims, 2 Drawing Figs.

1U.S.C|l 239/419, 239/102,239/428,239/596,239/600 11m. Cl F236 11/116 Fieldofsearch 239/4193, 419, 424.5, 427.3, 428, 596,600, 406, 418, 427,

102, DIG. 20 therefrom,

O 26 28 42 gap- Q" 48 (l/Yl/Plll/i" 40 V 32 30,; 53 l6 ABSTRACT: Paint sprayer with nozzle mounted in a chamber of an air cap adapted to be secured to a conventional compressed-air gun adjacent separate paint and air outlets PATENTEU SEP28 nan v" fakv Illlllll" w will .0

SPRAY NOZZLE ASSEMBLY OPEIRAIBILE AT LOW PRESSURE This invention relates to spraying paint.

Objects of the invention are to provide an improved paint sprayer capable of incorporating a conventional compressedair paint-spraying gun, and in which even very heavy paint can be finely atomized, and yet which can be operated at low pressure and with low air consumption, and is simple, reliable, and inexpensive to make and use.

The invention features an air cap adapted to be secured to a conventional compressed-air paint-spraying gun adjacent separate paint and air outlets therefrom, the air cap having an outlet and a chamber upstream of the outlet for receiving air and paint from the gun, and an atomizing nozzle mounted in a chamber upstream of the air cap outlet, the noule having a body defining an axial flow passage with a pair of coaxial radial holes thereinto spaced 180 apart intermediate the inlet and outlet ends of the passage, so that paint and air entering the air cap pass into the nozzle at its inlet end and through its radial holes, and the paint emerges from the air cap outlet atomized in a spray. In preferred embodiments the nozzle has a single outlet opening and the air cap has an end wall defining a single outlet opening aligned with, and of larger diameter than, the nozzle outlet opening; the nozzle has a flange at its outlet end and is mounted in an axial passage in the air cap with the flange against the air cap end wall, the axial passage of the air cap being of larger diameter than the nozzle body just upstream of the flange; and a perforated reflector is mounted at the upstream end of the axial passage of the air cap and is spaced from the nozzle.

Other objects, features, and advantages of the invention will be apparent from the following description of a preferred embodiment thereof, taken together with the drawings thereof, in which:

FIG. 1 is a view of a conventional paint sprayer modified to embody the invention, with the air cap partly broken away, some of the elements inside the air cap being shown in section; and

FIG. 2 is an exploded perspective view of some of the elements ofFIG. 1.

Conventional paint sprayer head 10, with needle valve paint outlet 12 surrounded by air outlets 114, is mounted inside air cap 16, which is adapted to be secured to a conventional compressed-air-operated spray gun (not shown) by threaded retainer ring 18. Cap 16 has an indicating groove 17 (FIG. 2).

Annular flange 20 of nozzle 22 is press fitted in the downstream end of axial bore 24 of cap 16, against flange 26 surrounding cap outlet 28 (outlet diameter 0.370 inch).

Disc-shaped reflector 30 (outside diameter 0.496 inch) is press fitted in counterbore 32 of cap 116, between nozzle 22 and head 10. Reflector 30 has a central hole 33 (diameter 0.1 l 1 inch) midway between two holes 34 (each 0.144 in diameter having axes spaced 0.290 inch and coplanar with the axis of hole 32. Central hole 33 is concentric with an imaginary circle (diameter 0.136 inch) containing the centers of four equally spaced holes 36 (diameter 0.135 inch) arranged symmetrically about the line ofcenters of holes 33 and 34.

Noule 22 has a cylindrical wall 40 (outside diameter 0.346 inch, inside diameter 0.260 inch) open at its outlet end across countersink 42, which is surrounded by flange 20. Axial inlet 44 (diameter 0.025 inch) is provided in upstream end wall 46 which is relieved to provide two openings 48 into the nozzle, each opening 43 having the shape of a segment of a circle. The centers of openings 48 are respectively spaced angularly 90 from the centers of holes 34. Two opposing coaxial radial holes 50 (each of diameter 0.073 inch) through wall 40 are 180 apart and tangent to countersink 42. The centers of inlet 44, openings 48, and holes 50 all lie in a single plane which is horizontal when the sprayer is oriented with groove 17 facing up (FIG. 2).

Additional nozzle dimensions are:

Length between downstream face of wall 46 and upstream end of countersink 42 0.148" Overall length of nozzle 0.209" Depth of countersink 42 0.029" Width of wall 46 between openings 48 0.190" Diameter of bore 24 upstream of flange 20 0.442"

In operation, paint, and air at greater than atmospheric pressure are supplied to head 10 (held. so that groove 17 faces up) in conventional manner and respectively enter cap 16 through outlets 112 and 14. The paint passes through hole 33 and most of the air passes through holes 34. Holes 36 relieve by about 20 percent the hydraulic pressure drop across hole 33, thus reducing the required paint pressure. Mixing takes place in bore, 24, with paint and air in varying proportion passing into the nozzle through inlet 44, openings 48, and holes 50. Nozzle 22 atomizes the paint, which emerges from outlet 28 in a vertical, fan-shaped spray of very small droplets, due to the arrangement of holes 50 in a single opposing pair (although the spray would still be fan-shaped if there were e.g., a pair of additional radial holes respectively spaced from and smaller than holes 50). Reflector 30 minimizes backspraying of paint against head 10, improves atomization, and, by the arrangement of holes 34 spaced 90 respectively from holes 50 and openings 43, increases the width of the fan.

In a typical operation, paint flow is 23 oz./min., and air flow is 15 c.f.m. at 60 p.s.i.g. Air consumption decreases as paint flow is increased.

The subject matter disclosed herein relating to spraying paint with an atomizing nozzle, to supplying the nozzle through a reflector, and to provision of a fan-shaped spray, was the sole invention of Nathaniel Hughes.

Other embodiments will occur to those skilled in the art and are within the following claims.

What we claim is:

11. Paintspraying apparatus comprising an air cap adapted to be secured to a conventional compressed-air paint-spraying gun adjacent separate paint and air outlets therefrom, said air cap having a portion defining an outlet, and a chamber upstream of said air cap outlet for receiving air and paint from said separate outlets, and

an atomizing nozzle mounted in said chamber adjacent said air cap outlet and comprising a body defining an axial flow passage having inlet and outlet ends, and

a pair of coaxial radial holes into said passage spaced apart intermediate said ends,

said inlet end of said axial flow passage and said coaxial radial holes each being in communication with both said paint and air outlets, whereby said paint and air received in said chamber pass into said flow passage at said inlet end and through said radial holes, and emerge from said air cap outlet, said paint emerging atomized in a spray.

2. The apparatus of claim 1 wherein said air cap has an end wall defining a single outlet opening aligned with a single outlet opening of said nozzle.

3. The apparatus of claim 2 wherein said nozzle has a flange surrounding said nozzle outlet opening, and said nozzle is mounted with said flange against said end wall.

4. The apparatus of claim 2 wherein said outlet opening of said air cap is of diameter at least as great as that of said nozzle outlet opening.

5. The apparatus of claim 4 wherein said outlet opening of said air cap is of greater diameter than said nozzle outlet openmg.

6. The apparatus of claim 3 wherein said chamber is an axial passage in said air cap of diameter greater than that of said nozzle body just upstream of said flange.

7. The apparatus of claim 1 wherein a perforated reflector is mounted in said air cap at the upstream of said chamber. 

1. Paint-spraying apparatus comprising an air cap adapted to be secured to a conventional compressed-air paint-spraying gun adjacent separate paint and air outlets therefrom, said air cap having a portion defining an outlet, and a chamber upstream of said air cap outlet for receiving air and paint from said separate outlets, and an atomizing nozzle mounted in said chamber adjacent said air cap outlet and comprising a body defining an axial flow passage having inlet and outlet ends, and a pair of coaxial radial holes into said passage spaced 180* apart intermediate said ends, said inlet end of said axial flow passage and said coaxial radial holes each being in communication with both said paint and air outlets, whereby said paint and air received in said chamber pass into said flow passage at said inlet end and through said radial holes, and emerge from said air cap outlet, said paint emerging atomized in a spray.
 2. The apparatus of claim 1 wherein said air cap has an end wall defining a single outlet opening aligned with a single outlet opening of said Nozzle.
 3. The apparatus of claim 2 wherein said nozzle has a flange surrounding said nozzle outlet opening, and said nozzle is mounted with said flange against said end wall.
 4. The apparatus of claim 2 wherein said outlet opening of said air cap is of diameter at least as great as that of said nozzle outlet opening.
 5. The apparatus of claim 4 wherein said outlet opening of said air cap is of greater diameter than said nozzle outlet opening.
 6. The apparatus of claim 3 wherein said chamber is an axial passage in said air cap of diameter greater than that of said nozzle body just upstream of said flange.
 7. The apparatus of claim 1 wherein a perforated reflector is mounted in said air cap at the upstream end of said chamber. 